1. Field of the Invention
The present invention relates generally to polarizing plates and image displays including the same.
2. Description of the Related Art
A liquid crystal display (LCD) is one of the various image displays available. An LCD is a device that displays, for example, letters and images using electrooptic properties of liquid crystal molecules. Generally, an LCD is provided with a liquid crystal cell and two polarizing plates disposed on both sides of the liquid crystal cell. Generally, the polarizing plates each have a structure in which a protective film is attached to both sides of a polarizer with an adhesive. Conventionally, a triacetyl cellulose (TAC) film is widely used as the protective film. Furthermore, the polarizing plates may be subjected to a hard-coating (hardening) treatment. The hard-coating treatment is carried out by forming a hard-coating layer on the TAC film using a photocurable resin. Commonly, one of the TAC films provided on both sides of the polarizer is subjected to the hard-coating treatment (for instance, see Japanese Patent Application Laid-Open (JP-A) No. 2005-338550).
On the other hand, with increased applications of LCDs, for example, mobile devices such as cellular phones and car navigation units, there are demands for the polarizing plates to have an improved hardness. Furthermore, there also are demands for the polarizing plates to have a reduced thickness. In order to meet these demands, a polarizing plate has been proposed in which the TAC film is omitted and a protective layer is formed on the surface of a polarizer using a photopolymerizable compound (Japanese Patent Application Laid-Open (JP-A) No. 2005-10329).
With respect to the improvement in hardness, conventionally there has been no polarizing plate exhibiting a hardness of at least 6H in the pencil hardness test method described in JIS K 5400 (1990 version). Moreover, the polarizing plate wherein the TAC film is omitted and a protective film is formed on the surface of a polarizer using a photopolymerizable compound to reduce the thickness, has a problem with polarization properties.